This invention relates to a clutch system of the friction type placed in a power transmission system. Typical clutch systems include a clutch input such as a clutch basket, a clutch output such as a center clutch, and one or more plates making up a clutch pack and disposed between the clutch input and clutch output. When the clutch pack is compressed, the clutch input and clutch output become rotationally coupled. The clutch pack is typically compressed by a pressure plate; the pressure plate typically providing a compressive force via a spring mechanism or through a centrifugally actuated mechanism.
Typically, such clutch systems include a clutch disengagement system consisting of a lever mechanically coupled to the pressure plate such that when the lever is actuated, the pressure plate's compressive force on the clutch pack is removed, disconnecting the rotational coupling between the clutch input and clutch output. Clutch disengagement systems typically couple the lever to the pressure plate mechanically through a hydraulic actuation system or a cable actuation system.
Most motorcycles incorporate a manual transmission coupled to the engine via a multi-plate clutch assembly. Typically, the multi-plate clutch is engaged/disengaged by the driver via a lever mounted on the handlebar. Although the lever operated clutch allows the driver to control the clutch engagement/disengagement, often times motorcycle drivers find the clutch lever difficult to operate smoothly. New riders have difficulty adjusting to smoothly engaging the clutch while operating the throttle to move the vehicle from a standing start. Experienced riders may need to partially disengage the clutch when traveling slowly to allow the engine to continue running without stalling. Motorcycle racers often have a difficult time controlling the engagement of the clutch and the application of the throttle to maximize acceleration. Off-road motorcycle racers often need to stop the rear wheel suddenly with the rear brake, causing the engine to stall if the clutch is not first disengaged. An automatic clutch can help overcome many of the problems associated with a manual clutch.
U.S. patent application Ser. No. 12/412,245 discloses an automatic clutch system incorporating an expanding friction disk and is incorporated herein by reference. One of the benefits of the improved automatic clutch system is the ability for the operator to override the automatic engagement of the clutch via a clutch lever without a significant change in how the clutch lever responds due to the centrifugal mechanism in the automatic clutch. Such a clutch system requires the pressure plate to be lifted away from the clutch pack to function properly. In application Ser. No. 12/412,245, lifting the pressure plate away from the clutch pack is accomplished with an adjuster within the engine cases.
However, for some motorcycle operators, the ability to adjust the position of the pressure plate without opening the engine cover to gain access to the clutch is important. Being able to adjust the position of the pressure plate externally allows the operator to make adjustments to the clutch system to compensate for clutch pack wear for example. By adjusting the position of the pressure plate so that it comes in contact with the clutch pack, allows the operator to quickly and easily configure the clutch so that when the engine is not spinning, the clutch is engaged. In this configuration, the clutch operation is similar to a manual clutch and allows the operator to “bump start” the engine. When the engine is off, with a gear selected and the clutch lever engaged, rolling the motorcycle at sufficient speed and then suddenly releasing the clutch lever to engage the clutch, can start the engine.
For typical hydraulic clutch disengagement systems, no such provision exists for positioning the pressure plate relative to the clutch pack through an external adjuster.
Hydraulic clutch disengagement systems are well known in the art and are typified by systems made by Magura and Brembo and included on motorcycles such as those provided by KTM such as the KTM model year 2010 KTM 250 XCW.
A typical hydraulic clutch disengagement system includes a master cylinder incorporating a reservoir for hydraulic fluid and a lever acting on a piston. A slave cylinder incorporates a bore and a piston; the piston typically acts upon the clutch throwout to lift the pressure plate for disengagement. A hydraulic line typically couples the master and slave cylinders and provides a conduit for the hydraulic fluid.
Therefore a need exists for an adjustment mechanism with adjustment access external to the inside of the engine that can lift the clutch pressure plate to create a gap between the pressure plate and clutch pack. For typical hydraulically actuated clutch disengagement systems, the adjustment mechanism should maintain the use of the clutch lever maintaining the clutch levers capability to manually lift the pressure plate.
It is therefore an object of the present invention to provide an adjuster mechanism with adjustment access external to the inside of the engine, for a typical hydraulic clutch disengagement system that allows a gap between the pressure plate and clutch pack to be created and adjusted while retaining the capability to manually lift the pressure plate to force disengagement of the clutch.
The present invention for typical hydraulically actuated clutch disengagement systems is disclosed in FIGS. 1 through 6.